Abstract not found

This thesis presents accounts of a range of linguistic phenomena in an extended categorial framework, and develops proposals for processing grammars set within this framework. Linguistic phenomena whose treatment we address include word order, grammatical relations and obliqueness, extraction and island constraints, and binding. The work is set within a flexible categorial framework which is a version of the Lambek calculus (Lambek, 1958) extended by the inclusion of additional type-forming operators whose logical behaviour allows for the characterization of some aspect of linguistic phenomena. We begin with the treatment of extraction phenomena and island constraints. An account is developed in which there are many interrelated notions of boundary, and where the sensitivity of any syntactic process to a particular class of boundaries can be addressed within the grammar. We next present a new categorial treatment of word order which factors apart the specification of the order of a h...

This thesis presents NL-Soar, a detailed computational model of human sentence comprehension that accounts for a broad range of psycholinguistic phenomena. NL-Soar provides in-depth accounts of structural ambiguity resolution, garden path effects, unproblematic ambiguities, parsing breakdown on difficult embeddings, acceptable embeddings, immediacy of interpretation, and the time course of comprehension. The model explains a variety of both modular and interactive effects, and shows how learning can affect ambiguity resolution behavior. In addition to accounting for the qualitative phenomena surrounding parsing breakdown and garden path effects, NL-Soar explains a wide range of contrasts between garden paths and unproblematic ambiguities, and difficult and acceptable embeddings: the theory has been applied in detail to over 100 types of structures representing these contrasts, with a success rate of about 90%. The account of real-time immediacy includes predictions about the time course of comprehension and a zero-parameter prediction about the average rate of skilled comprehension. Finally, the theory has been successfully applied to a suggestive range of cross-linguistic examples, including constructions from head-final languages such as Japanese.

This dissertation examines the "free" word order or scrambling phenomena in German and Korean from the perspective of constraint interaction in Optimality Theory. To overcome the problems raised in single-component analyses in explaining word order variation, I propose an `interface' approach in which the constraints from several different components of grammar participate, compete, and interact with one another. That is, various word orders are considered to be motivated and constrained by interactions among syntactic, semantic, and discourse principles of these languages. As the constraints from different modules of grammar are highly conflicting, I utilize Optimality Theory to demonstrate how the constraints interact and resolve conflicts among one another. In this approach, each scrambled variant, i.e. a sentence with a particular word order, is conceived of as the "optimal" output, which instantiates the syntactic, semantic, and discourse-contextual information given in the input....

Many theories have been proposed to explain difficulty with center embedded constructions, most attributing the problem to some kind of limited capacity short-term memory. However, these theories have developed for the most part independently of more traditional memory research, which has focused on uncovering general principles such as chunking and interference. This article attempts to gain some unification with this research by suggesting that an interesting range of core sentence processing phenomena can be explained as interference effects in a sharply limited syntactic working memory. These include difficult and acceptable embeddings, as well as certain limitations on ambiguity resolution, length effects in garden path structures, and the requirement for locality in syntactic structure. The theory takes the form of an architecture for parsing which can index no more than two constituents under the same syntactic relation. A limitation of two or three items shows up in a variety o...

We present a detailed process theory of the moment-by-moment working-memory retrievals and associated control structure that subserve sentence comprehension. The theory is derived from the application of independently motivated principles of memory and cognitive skill to the specialized task of sentence parsing. The resulting theory construes sentence processing as a series of skilled associative memory retrievals modulated by similarity-based interference and fluctuating activation. The cognitive principles are formalized in computational form in the Adaptive Control of Thought–Rational (ACT–R) architecture, and our process model is realized in ACT–R. We present the results of 6 sets of simulations: 5 simulation sets provide quantitative accounts of the effects of length and structural interference on both unambiguous and garden-path structures. A final simulation set provides a graded taxonomy of double center embeddings ranging from relatively easy to extremely difficult. The explanation of center-embedding difficulty is a novel one that derives from the model’s complete reliance on discriminating retrieval cues in the absence of an explicit representation of serial order information. All fits were obtained with only 1 free scaling parameter fixed across the simulations; all other parameters were ACT–R defaults. The modeling results support the hypothesis that fluctuating activation and similarity-based interference are the key factors shaping working memory in sentence processing. We contrast the theory and empirical predictions with several related accounts of sentence-processing complexity.

While there is no interesting limitation on the degree of right-embedding in acceptable sentences, center-embedding is quite severely restricted. Similarly, while there is no interesting bound on the number of nouns that can occur in acceptable noun compounds, there is a very low bound on the number of causative morphemes that can occur in the verb compounds of agglutinative languages. Turning to the clause-final verb clusters of West Germanic languages, we find another similar bound. A cluster including verbs from one embedded clause may beacceptable, but clusters formed from the verbs of two or three or even more deeply embedded clauses are much more awkward (regardless of whether the subject-verb dependencies are crossing or nested). And in languages that allow multiple wh-extractions from a single clause, extractions of more than one element with a given case quickly become unacceptable. More careful experimental study of the nature of these limitations is needed, in a range of languages, but here a preliminary attempt is made to subsume them all under a single generalization, a version of the familar idea that the human parsing

The research of the last four decades suggests strongly that abstract laws of significant generality underlie much of the superficial complexity of human language. Evidence in favor of this conjecture comes from two different types of facts. First, there are cross-linguistic facts. Investigation of unfamiliar and typologically diverse languages is regularly illuminated by what we already know about other

istic methods for syntax, just as for a long time McCarthy and Hayes (1969) discouraged exploration of probabilistic methods in Artificial Intelligence. Among his arguments were that: (i) Probabilistic models wrongly mix in world knowledge (New York occurs more in text than Dayton, Ohio, but for no linguistic reason), (ii) Probabilistic models don't model grammaticality (neither Colorless green ideas sleep furiously nor Furiously sleep ideas green colorless have previously been uttered -- and hence must be estimated to have probability zero, Chomsky wrongly assumes -- but the former is grammatical while the latter is not, and (iii) Use of probabilities does not meet the goal of describing the mind-internal I-language as opposed to the observed-in-the-world E-language. This chapter is not meant to be a detailed critique of Chomsky's arguments -- Abney (1996) provides a survey and a rebuttal, and Pereira (2000) has further useful discussion -- but some of these concerns are still importa

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